static bool isValidCoroutineContext(Sema &S, SourceLocation Loc,
StringRef Keyword) {
// 'co_await' and 'co_yield' are not permitted in unevaluated operands.
if (S.isUnevaluatedContext()) {
S.Diag(Loc, diag::err_coroutine_unevaluated_context) << Keyword;
return false;
}
// Any other usage must be within a function.
auto *FD = dyn_cast<FunctionDecl>(S.CurContext);
if (!FD) {
S.Diag(Loc, isa<ObjCMethodDecl>(S.CurContext)
? diag::err_coroutine_objc_method
: diag::err_coroutine_outside_function) << Keyword;
return false;
}
// An enumeration for mapping the diagnostic type to the correct diagnostic
// selection index.
enum InvalidFuncDiag {
DiagCtor = 0,
DiagDtor,
DiagCopyAssign,
DiagMoveAssign,
DiagMain,
DiagConstexpr,
DiagAutoRet,
DiagVarargs,
};
bool Diagnosed = false;
auto DiagInvalid = [&](InvalidFuncDiag ID) {
S.Diag(Loc, diag::err_coroutine_invalid_func_context) << ID << Keyword;
Diagnosed = true;
return false;
};
// Diagnose when a constructor, destructor, copy/move assignment operator,
// or the function 'main' are declared as a coroutine.
auto *MD = dyn_cast<CXXMethodDecl>(FD);
if (MD && isa<CXXConstructorDecl>(MD))
return DiagInvalid(DiagCtor);
else if (MD && isa<CXXDestructorDecl>(MD))
return DiagInvalid(DiagDtor);
else if (MD && MD->isCopyAssignmentOperator())
return DiagInvalid(DiagCopyAssign);
else if (MD && MD->isMoveAssignmentOperator())
return DiagInvalid(DiagMoveAssign);
else if (FD->isMain())
return DiagInvalid(DiagMain);
// Emit a diagnostics for each of the following conditions which is not met.
if (FD->isConstexpr())
DiagInvalid(DiagConstexpr);
if (FD->getReturnType()->isUndeducedType())
DiagInvalid(DiagAutoRet);
if (FD->isVariadic())
DiagInvalid(DiagVarargs);
return !Diagnosed;
}
